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Continuous integration (CI) is a process by which we verify our project upon every change that occurs in the codebase. It can be as simple as installing the dependencies and compiling the project. CI usually runs a few different tasks in a defined order for every code change. For a feature branch, you should merge it only if it’s passing the CI. The main branch should be almost always passing; any issue on it will affect everybody on the team, so fixing it should be a priority if some regression happens.